Method and apparatus for completing wells



process and. apparatus for completing gas and oil obtained fromPatentedAug. i8, 1942 l UNITED STATES PATENT OFFICE Alllqlxlyg roncommer@ mamon AND James S. Crump, Houston,

'.lex.,V assigner to i Standard Oil Development Company, a corporationoi' Delaware application August 2e, 1939, sensi No. 292,011

4The prsent invention relates to an improved l'oil wells.

'An object of the present invention is to complete high gas-oil ratiooil wells vso that'oil containing a low gas ratio may be obtained fromthe Well. l

Inv accordance withmy invention a mixture of a producing formationpenetrated by a-borehole is separated within the borehole so that oilis'obtained which has a low oil-gas ratio and in addition gas isobtained from the well.' rIjhe gas may be obtained at a pressuresubstantially the same as that existing in the producing formation andmay be returned to the producing zone by Vrepressuring by theexpenditure of very little additional energy. Other objects andadvantages may be seen from the following description taken with thedrawing in which the sole ligure is asectional view through a wellproducing oil and gas havingapplied thereto a modiiication of thepresent invention, As shown by the'igure, `a borehole I penetrates aproducing formation 2. is carried down Ia substantial distance'below theproducing formation' 2 for reasons which will later be apparent. Acasing -3 having its `end closed by clogre l isv lowered into theborehole so that end ing formation 2. This casing is provided with acement plug i above andvcement plug 8 below producing formation 2, inorder to prevent Iluid leakage between the wall of the borehole ThisAborehole ed to a diil'erent source s claims. (ci. 16e-z) y NeilanCompany. Regulatorspf this type have the valve mechanically connected toa diaphragm with each side ofthe diaphragm fluidly connectof pressure.

In the schematic drawing,A regulator Il is provided with diaphragm I8-connected tovalve Ill by mechanical linkage I8. Pressure in casing 3has access to one side of diaphragm I8 through at a substantial distancebelow produc and the casing as is well understood in the art.

Casing 3 is perforated 'with periorations 'I at a point oppositeformation! so that iluid from the formation may enter directly into thecasing.` A tubing 8 provided with check valve 8 is placed within casing3 so that its lower end reaches well below' the producing formation 2..

l valve I8 are well known tothe art. A satisfactory regulator for usein: practicing the present invention is describedznand illustrated onpages 43. 44 and Fig. 24 of the University ot Oklahoma Bulletin of the1938 Southwestern Gas Measurement Short Course,

' New Series No.. 748, and another is back pres- 'Sllre regulator #27manufactured by the Mason.

space between the casing and the .Iltis `causes the difference in lineI2 and pressure ingtubing 8 has access to the'other'side of thediaphragm through line 28. l vAs thus arranged, regulator. II will closevalve I8 when pressure in the upper end of tubingI 3 approaches thepressure in the upper end of the casing, so the difference in the twopressures is small. In a similar manner regulator II will openvalve I8when a substantial decrease in the pressure in the upperend of tubing 8pressurebetween these two pipes to become relatively large. l

The formation pressure in producing formatio 2 causes a mixture -of oiland gas to owthrough the perforations 1 and into casing 3. When thismixture enters the space within Vcasing 8 the reduction in pressure andchange in direction of the `iluid allows the oil to separate from thegas. The oil is heavier so it drops down and rests upon the bottom 4 ofthe casing while the gas iillsthe upper portion of casing 3. After acertain lperiod of time the system will come to equilibrium with thelevel of the oil'within casing 3 being at point I3. .It isevident thatit after the system reaches this condition the valve I8 is opened theposition of liquid level I3 will drop the gas pressure in thecasingforcing the oil up through tubing 8 and out of the well at the.surface of the earth. If this valve allowed to remain open, eventually.all oi Y, the oil from casing 8 will be produced and a mixture 'of gasand oil as it comes from the formation 2 will then ow through tubing 8.

Inaccordance with my preferred method of carrying out the invention theregulator II `is set to close valve III as soon as the oil level I 3drops to such a low point that it no longer forms a liquid seal I8 isprovided with a small by-pass I4 which allows, gas to be produced fromthe tubing at a slow rate. After ,valve I8 has closed the bypass Ilallows the gas withwhich tubing-8has become filled to be'slowly releasedso that as the oil `is produced from formation 2` and illls the lowerend oi' casing v8 the oil level in tubin'g 8 is allowed to slowlylrise.f After `the oil level is tubing .I rises to such a height that theand allows a mixture of oil and gas to be produced from the well.Valve.l

' a liquid seal.

gas-oil ratio oil well having its pressure difference between the oil intubing 8 and that in the upper end of casing 3 reaches a predeterminedamount the regulator II opens valve I0 and allows oil to be once againproduced through tubing 8 until the oil level I3 drops so that there isno longer a liquid' seal and the pressure in tubing 8 and that in casing3 are partially equalized, when the valve i0 is again closed and thecycle is repeated.

' As a modification of the present invention the regulator always abovethe lower end of tubing 8 and forms When this modification of theinvention is desired, the regulator II opens valve I and allows oil tobe produced, the liquid level I3 dropping. AS the liquid pressure in thetop of tubing 8 gradually decreases because there isnot so much oil incasing 3 to balance the liquid in tubing 8. When the liquid level I3 isnear the bottom of tubing- 8 the pressure becomes 'so low that theregulator closes Valve I0 and allows oil from formation 2 to flow into'the casing and partially balance the liquid in tubing 8. When the heightof liquid I3 has risen to a certain distance the pressure in tubing 8will be increased, regulator II will open valve I0, and the cycle willbe repeated,

It is evident that if production of fluid through tubing 8 does notproduce sufficient drop in the formation pressure gas may be withdrawnfrom the upper part of casing 3 by means of connection I5 provided withvalve I5. The gas removed through Valve I6 is at a very high pressureand is particularly suitable for repressuring.

While I have disclosed several specific modifications of carrying o'utmy invention, it is evident that other procedures may be used forcarrying out the broad features of the present invention and I do notintend to be bound by the specific examples but wish to claim myinvention as broadly as the prior art permits.

I claim:

1. Apparatus for producing fluid from a high borehole penetrating asubstantial distance below a producing formation comprising, incombination, a casing arranged within said borehole with its lower end asubstantial distance below said producing formation, perforations insaid casing opposite said producing formation, a string of tubingarranged in said casing with its lower end adjacent the lower end ofsaid borehole, a closure for the upper end of said casing, a valvearranged in the upper end of said string of tubing, a relatively smallby-pass around said valve and a pressure regulator arranged to open saidvalve when the may be set so that the oil level I3 is level I3 drops thepressure in the upper end of the tubingbecomes less than that in theupper end of the casing by a predetermined amount, and to close thevalve when the pressure difference between thesel two points becomesless than a predetermined value.

2. Apparatus in accordance with claim 1 in which a conduit controlled bya valve is attached to the upper end of said casing in fluidcommunication with the interior thereof, l

3. In a high gas-oil ratio oil well having a borehole penetrating asubstantial distance below a producing formation with a casing arrangedtherein, means for fluid communicationV between said producing formationand the interior of said casing, a string of tubing within said casingwith its lower end adjacent the lower end of said borehole, and aAclosure for the upper end of said casing, means for controlling the flowof iiuid through said tubing vcomprising in combination a valve arrangedin the upper end of said string of tubing, a small by-pass around saidvalve, a pressure regulator in fluid communication with the upperportion of said casing arranged to open said valve when the pressure inthe upper end of the tubing becomes less than that in the upper end ofthe casing by a predetermined amount, and to close the valve when thepressure diiference between these two points becomes less than apredetermined value.

4. A process for producing fluid from a high gas-oil ratio oil well inwhich the bore hole penetrates a substantial distance below. a producingformation and is provided with a casing perforated a-t the producingformation and lwith a string of tubing having its induction end asubstantial distance .below the producing formation comprising the stepsof allowing liquid to accumulate in the bottom of the borehole until itsupper surface is substantially above the induction end of said tubing,producing liquid through said tubing until said liquid surface dropsbelow the induction end of the tubing and gas fills the tubing, bleedinggas from the upper end of said tubing at a rate slower than the rate ofliquid accumulation in said borehole whereby liquid accumulates in thebottom of the well and rises within said tubing and again allowingliquid to be produced through said tubing.

5. A process in accordance with claim 4 in which high pressure gasisnwithdrawn at the surface vof the earth from the space between thetubing and casing in order to allow liquid to accumulate in the bottomof the borehole at the desired rate.

I JAMES S. CRUMP.

